Re: When use triggers?

On Fri, May 18, 2018 at 9:35 AM, Vick Khera <vivek(at)khera(dot)org> wrote:

> On Wed, May 16, 2018 at 6:19 PM, hmidi slim <hmidi(dot)slim2(at)gmail(dot)com> wrote:
>
>> HI,
>>
>> I'm working on a microservice application and I avoid using triggers
>> because they will not be easy to maintain and need an experimented person
>> in database administration to manage them. So I prefer to manage the work
>> in the application using ORM and javascript.
>> However I want to get some opinions and advices about using triggers:
>> when should I use them? How to manage them when there are some problems?
>>
>
> I have used triggers to keep audit-logs of changes to certain columns in a
> table. For example, I want to know when a customer went "overdue" and then
> back to "active". The best place to create that log is in the database
> itself, since that also captures any manually updated rows (ie, those
> actions not initiated by the application code itself).
>
> I have also used triggers to ensure data consistency and enforce state
> diagram transition rules for status columns in a table. These help capture
> logic errors in application code. For example, if your state diagram allows
> A -> B <-> C, then the trigger would disallow a transition from B or C to
> A, disallow A -> C, but allow C -> B and B -> C and A -> B.
>
> To manage them, we treat them like all DDL changes: everything is done via
> SQL script, and those are tracked using our version control software, go
> through developer testing then staging testing, then finally production.
>

> I have used triggers to keep audit-logs of changes to certain columns in
a table
Another good use for triggers is to maintain customer balance..EG: An
INSERT, UPDATE or DELETE involving a customer payment
(or in the case of banks (deposit or withdrawals) would automatically
maintain the balance in the customer master record.

--
*Melvin Davidson*
*Maj. Database & Exploration Specialist*
*Universe Exploration Command – UXC*
Employment by invitation only!